1. Field of the Invention
The invention relates to an electroacoustic transducer having a substantially hollow symmetrical magnet system and having contact holding means which are retained in the inner zone of the magnet system and which hold spring contacts for the electrical connection of the transducer.
2. Description of the Related Art
Such a transducer of the type defined in the opening paragraph is known, for example, from International Patent Application No. WO 98/38832 A1 corresponding to U.S. Pat. No. 6,072,886. In the known transducer, the contact holding means is formed by a pot-shaped contact holder having a bottom wall and a hollow cylindrical circumferential wall which is integrally connected to the bottom wall in the peripheral area of the bottom wall. Two substantially U-shaped spring contacts are mounted in the pot-shaped contact holder, one limb of each of said spring contacts extending parallel to the bottom wall and having a terminal lug which extends through the bottom wall of the contact holder. In the known transducer, the two spring contacts must be inserted into the pot-shaped contact holder in the direction of the transducer axis and must be retained in the pot-shaped contact holder by separate means, for example, with the aid of an interlocking connection or an adhesive joint. The construction known from the known transducer has proven itself millions of times in practice.
The known construction described hereinbefore is subject to limitations in that with the trend towards further miniaturization of such a transducer, the known construction leads to problems because, in the case of further miniaturization, the wall thicknesses of the bottom wall and the circumferential wall of the pot-shaped contact holder become so small that problems may arise with the strength of the pot-shaped contact holder, and production problems during the production of the plastic pot-shaped contact holder, as well as problems with the assembly and fastening of the spring contacts in the pot-shaped contact holder.
It is an object of the invention to provide a solution for a transducer of the type defined in the opening paragraph which enables a further miniaturization of such a transducer to be achieved and, in spite of the further miniaturization, guarantees a stable construction in the area of the contact holding means.
In order to achieve the aforementioned object, characteristic features in accordance with the invention are provided, in a transducer in accordance with the invention, in such a manner that a transducer in accordance with the invention can be characterized in the manner defined hereinafter, namely:
An electroacoustic transducer having a magnet system which is substantially centro-symmetrical with respect to a transducer axis and which is substantially hollow cylindrical and includes an annular magnet arranged parallel to a plane which extends transversely to the transducer axis, which magnet system surrounds an inner zone, and having contact holding means which, at least for the greater part, is accommodated in the inner zone and is retained in the inner zone, and having two spring contacts for the electrical connection of the transducer, the spring contacts being retained with the aid of the contact holding means and each being formed with at least one bend, wherein the contact holding means has two contact holding elements adjoining one another along two identically shaped bounding surfaces extending transversely to the plane, and wherein each contact holding element has a holding chamber opening towards its bounding surface, the holding chamber of each contact holding element accommodating one of said spring contacts inserted into the holding chamber from the side of the bounding surface.
As a result of the provision of the measures in accordance with the invention, it is achieved that, even in the case of a very small size, a construction of the contact holding means having a high mechanical stability is obtained in a constructionally very simple and cheap manner. Furthermore, this has the advantage that, apart from the contact holding elements, no further additional means are required in order to retain the spring contacts because the spring contacts are simple retained by interlocking with the contact holding elements.
A transducer in accordance with the invention may include not only two contact holding elements and two spring contacts, but it is likewise possible to provide three or four contact holding elements and, consequently, three or four spring contacts. In a transducer in accordance with the invention, the bounding surfaces of the contact holding elements, along which the contact holding elements adjoin one another, may have a shape which is inclined with respect to the plane of the annular magnet, this shape corresponding to a flat, of alternatively a curved, bounding surface. However, it has proven to be very advantageous when the preferably two contact holding elements adjoin one another along two bounding surfaces which extend parallel to the transducer axis and which preferably extend through the transducer axis. This is advantageous in view a construction of the contact holding elements which is as simple as possible.
It has proven to be particularly advantageous when the two contact holding elements in a transducer in accordance with the invention are wholly identical. This is particularly advantageous in view of a cost-effective production and, above all, in view of a simple automated production process.
It has further proven to be advantageous when each contact holding element has a raised portion and a recess in the area of its bounding surface because these means ensure a simple positioning of the contact holding elements with respect to one another.
In this connection, it has further proven to be very advantageous when the raised portion of one contact holding element is used for securing a portion of the spring contact in the other contact holding element. In addition to the reliable positioning of the spring contact this also has the advantage that, in the case that a spring contact has not been inserted deep enough into the holding chamber.
Tests have proven that it is very advantageous when each spring contact has a first portion and a second portion as well as a U-shaped third portion, because such a construction ensures a particularly reliable retention and a particularly reliable contacting.
In a transducer in accordance with the invention, two contact holding elements, combined to form a contact holding means, may form a contact holding means of, for example, square cross-sectional shape in a direction transverse to the transducer axis. However, it has proven to be particularly advantageous when two contact holding elements together form a substantially cylindrical contact holding means, which is pressed into the inner zone of the magnet system, because this ensures a particularly reliable retention and an exact positioning of the contact holding means and, consequently, of the spring contacts.
The above-mentioned as well as further aspects of the invention will become apparent from the embodiment described hereinafter by way of example and will be elucidated with reference to this example.